missing files

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/util/sstream.h

@@ -0,0 +1,21 @@
+
+
+/*
+Copyright (c) 2013 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+
+Author: Leonardo de Moura
+*/
+#pragma once
+#include <sstream>
+#include <string>
+
+namespace lean {
+/** \brief Wrapper for std::ostringstream */
+class sstream {
+    std::ostringstream m_strm;
+public:
+    std::string str() const { return m_strm.str(); }
+    template<typename T> sstream & operator<<(T const & t) { m_strm << t; return *this; }
+};
+}